Wave-signal receiver-transmitter system



Nov. 23, 1948. l.. R. MALLING WAVES GNAL RECEIVER-TRANSMITTER' ASYSTEM Filed March 7, 1944 Patented Nov. 23, 1948 'v UNITED STATESA PATENT OFFICE WAVE-SIGNAL RECEIVER-TRANSMITTER SYSTEM Leonard B. Mailing, San Diego, Calif., assignor, by mesne assignments, to Haleltlne Research, Inc., Chicago, Ill., a corporation of Illinois Application March 7, 1944, Serial No. 525,431

',Ihis invention -relates to wave-signal translating systems and more particularly to two-way radio-communication systems of a type in which the field intensity of wave signals transmitted by a responding unit of the system in response to a signal from a distant source is controlled inversely in accordance with the ileld intensity of the wave signals received by that unit from4 the source.

In two-way radio-communication systems which heretofore have been employed, the iield intensity of the signal transmitted by the respectrum more efiiciently utilized when signals' are transmitted from responding units having eld intensities varying in accordance with the received signal field intensity at the individual responding units. Specifically, it is desirable to control the field intensity of the signal emanating from a respondingunit inverselyin accordance with the eld intensity of the signal received by that unit. l

It is particularly useful to control the field intensities of signals transmitted by a responding unit in the manner just mentioned when relative movement exists between the twounits oi a two-way radio-communication system, since then the power output of one of the units can be regulated according to the varying intensity of received signals as inuenced by the changing distance, geography, atmospheric conditions, or other factors existing between the'two units. Additionally, power is expended only in accordance with the needs of altering situations, thus prolonging the life of equipment.

'l Claims. (CI. Z50- 13) In addition to controlling the field intensity of a signal transmitted by a responding unit in accordance with the iield intensity oi a received signal at the unit, it is also expedient simultaneously to regulate the receiver' sensitivity in the same manner; For the reception of signals having high iield intensities, it is desirable to' operate a receiver with reduced sensitivity. es-

pecially for reception in the ultra-high-i'requency region above megacycles, to minimize the masking of the desired signal by receiver noise.

It is an object of the invention, therefore, to provide an improved wave-signal translating system which overcomes one or more of the above- 'mentioned disadvantages of the prior art systems.

It is a further object of the invention to provide in a two-way wave-signal communication system a responding unit which is eiective inversely to regulate, in response to the iield intensity of ,a received signal. the iield intensity at vthe responding unit of a signal which is transmitted in reply to the received signal.

It is another object of the invention to provide' a new and improved radio receiver-transmitter arrangement for a two-way communication system which not only regulates the sensitivity of its receiver butl also controls the power output of its transmitter inversely in accordance with the field intensity of a radio signal received by the arrangement.

In accordance with the invention, a radio l'eceiver-transmitter system comprises means at a point for receiving from a remote radio transmitting station during spaced receiving intervals radio signals having a eld intensity at that point which may vary and for transmitting during intervals intervening the receiving intervals reply radio signals. The system also includes "means responsive to the neld intensity of a radio signal received during a receiving interval for deriving a control effect having a duration coextensive with the next succeeding interval during which a reply radio signal is transmitted. The radio receiver-transmitter system further includes a control system responsive to the control eiect for controlling the field intensity at the above-mentioned point of the reply radio signal, transmitted during the aforesaid next succeeding interval, inversely in accordance with the field'intensity of the radio signal received during the above-mentioned receiving interval.

Also in accordance with the present invention, a wave-signal translating system comprises regenerative means at a point for receiving wave signals from -a remote source and vfor transmitting related wave signals in reply thereto. The system also includes means responsive to the fieldintensity of received wave signals at that point for deriving a control effect, and a control system responsive to the control effect and including quench-oscillator means for controlling regeneration in the regenerative means during receiving intervals to nrnvidaA gain-nnni-.rnlln cumin-nameanode and a source +B. The screen electrode of tube 4I is connected to a suitable source indicated -l-Sc. A cathode resistor 46 for tube 4I is bypassed to ground by a condenser 41.

The anode 'of amplifier tube 4I is lnductively coupled, by a winding 48 tuned by a condenser 49, to the anode of the diode rectifier 50. The cathode of rectier 50 is connected through a filter network comprising shunt condensers 5I and 52 panying drawing, and its scope will be pointed out in the appended claims.

Fig. 1 of the drawing is a circuit diagram, partly schematic, of a complete wave-signal translating system embodying one'form of the invention, while Fig. 2 comprises a block diagram of a modified wave-signal translating system in accordance with the invention.

Referring now more particularly to Fig. 1 of the drawing, there is illustrated a wave-signal f translating system comprising means at a point for receiving wave signals from a source and transmitting related wave signals thereto. 'I'his means comprises a circuit I0 including a tube I I. The tube II is utilized in a combination superregenerative receiving and transmitting system, normally referred to in the art as a transponder. As used ln this specification, the term transpondor is intended to describe a wave-signal translating system which includes a receiver and a transmitter so arranged that a predetermined answer or reply signal is transmitted -in response to a received interrogating signal. The system is provided with an antenna 22 which is inductively coupled to an inductor I2 and connected of tube iI and ground through a coupling con- I denser I8, the diode having a load resistor connected across its electrodes through a choke Winding 2l.

The system of Fig. 1 also comprises means re' sponsive to the field intensity of a received signal at the point of reception for deriving a control effect. This means comprises acontrol unit 60, the input circuit of which is connected across the diode load resistor 20, which unit will be more fully described hereinafter.

There is included -in the wave-signal translating system of the instant invention a control system responsive to the control effect which is developed in control unit 60 for controlling'the field intensity, at the point of reception,`of the above-mentioned related transmitted signal inversely in accordance with the field intensity of the received signal. This means comprises a quench amplifier tube 4I, a diode rectifier 50, and an amplifier 54. The input circuit of amplifier 4I is coupled to the output circuit of a conventional quench oscillator 40 through a coupling condenser 42 and to the output circuit of the control unit 60 by a`resistor 43. The quench amplifier circuit is conventional and includes a tunedanode circuit comprising an inductor 44 and a condenser 45 connected in parallel between the clllator 40.

and a choke winding 53 to the primary winding of the step-up transformer I1, which winding is also connected in circuit with the anode of amplifler 54. The cathode of this amplifier is grounded and suitable operating potentials are.

supplied to the screenand control electrodes from sources +B and -C, respectively, the latter being connected to the control electrode through a resistor 55. A blocking condenser 56 is connected between an intermediate point on winding 44 and the junction point between the choke I6 and the secondary winding of transformer I1.

There is also comprised in the arrangement of Fig. 1 a means responsive to the received wave signals for developing auxiliary signals. This means comprises an amplifier 51 which is connected between the output circuit of control unit 50 and a transmitter signal-developing system 58. The amplifier may be a conventional amplier and the system 58 may comprise suitable means well known in the art, such as a multivibrator, which is responsive to each or to predetermined ones of applied input signals for developing the auxiliary signal. The system 58 ls coupled to the input circuit of amplifier 54 through a coupling condenser 59.

Referring briefly to the operation of the system as a whole, but neglecting for the. moment that of control unit 60 as it affects the remainder of the system, an alternating potential is applied to the tuned circuit I2, I3 of the superregenerative circuit including tube Il by quench oscillator 40 through quench amplifier 4I to cause the regenerative circuit to fluctuate between an oscillating and nonoscillating condition at a rate corresponding to the operating frequency of the quench os- Any signal which is intercepted by antenna 22 and applied to the tuned circuit I2, I 3 causes oscillation of this circuit to begin sooner and to reach a higher amplitude than when no signal is being received. These oscillations of increased amplitude are applied to rectifier I9, wherein the modulation components are derived to develop across resistor 20 a pulsating unidirectional potential, for example, asignal having the ,wave form R, as when'pulse-type signals having steep wave fronts are being received. The abovedescribed operation is that of a conventional superregenerative receiver and detailed explanation is therefore deemed unnecessary.

The operation of the transmitter portion of the system will be described under the assumption that the-derived modulation components of the received signal comprise the pulse R, The pulse R is impressed on the input circuit of control unlt 60 and the signal which is derived therein, in a :manner to be explained subsequently, is applied to the input circuit of amplifier 51 and ls then translated to the transmitter signal-developing system 58, wherein an auxillary signal comprising an output signal, such as the pulse T, having predetermined characteristics is developed and applied to amplifier 54. Units 51 and 58 are designed to respond to input signals which vary over a wide amplitude range. The anode potential for amplifier 54 is derived to enable'the oscillator circuit to function as a power oscillator. The signal also modulates the radio-frequency signal developed bythe oscillator circuit I and there is transmitted from the antenna 22 a pulse-modulated carrier signal which is related to the received pulse R.

The above-described alternate reception of a wave signal from a source during spaced receiving intervals and transmission of a relatedwave signal thereto during intervals intervening the receiving intervals is, therefore, that of a conventional two-way communication system utilizing a superregenerative system with a common receiving and transmitting tube.

Referring now more particularly to the'control unit 6i), the latter comprises a limiter 6|, the input circuit of which is connected to the diode .load resistor 20 and the output circuit of which is connected to a diode rectifier 64 through a dierentiatingcircuit 52, a clipper 69, an amplifier 63, and a blocking condenser 65.. A resistor 66, which is by-passed for alternating currents by a condenser 68, is connected between 6 sistor 43 to the control electrode of quench am- Control unit 60 is so designed that it is responsive to the field intensity of a wave signal received during a receiving interval at the receiver for deriving a control effect having a duration at least coextensive with the next sucthe anode of tube 64 and ground and a resistor 61 is connected between the cathode and ground. 'Ihe units (5I-63, inclusive, and 69, comprising the limiter, the differentiating circuit, the clipper, and the amplifier may comprise suitable units that are well known in the art, and, hence, a detailed description is not required. The input circuit of quench amplifier 4l is connected to the anode of diode 64, while the input circuit of Coming now to the operation of the entire system in conjunction with the control unit 60, it will be seen that the derived pulse R is applied to the input circuit of control unit rlill. A predetermined time interval after the application of pulse R to thepinput circuit of the unit 60, the transmitter portion of the system is keyed by the signalderived by rectifier 54 and transmits a signal of comparatively long duration. This signal is also picked up by the receiver and rectied to develop a pulse signal RT for application with the signal R to control unit 60. Limiter Bi derives a pair of time-spaced pulse signals of wave form `R and RT and applies them to the diiierentiating circuit 62. Limiter 5l is designed so that it'clips the peak of the exceedingly strong pulse RT but translates the comparatively weak signal R Without alteration in wave form, even though the latter signal varies in amplitude over a wide range. The parameters of the differentiating circuit 62 are so selected that only the signal which has a steep wave front is eil'ectively translated, the output signal being as indicated. This output signal is applied to the clipper 69 which responds only to signals of one polarity and translates a signal, as indicated, to unit 63. After amplification in unit 63, which also removes residual traces of the transmitted pulse. the signal is applied to amplifier 51 and also to rectier 64. The latter derives a negative unidirectional potential for application through reamplifier 5l is connected to the cathode of diode ceeding interval during which a reply signal is transmitted. Preferably this control eiect is also coextensive with the next succeeding receiving interval. Specifically, a unidirectional control potential is developed in the output circuit thereof, which is proportional to the field intensity of a received signal. This control effect is applied'to the control electrode of quench ampliiier tube 4l, which operates as a class A amplifler, in the form of a negative bias of variable magnitude to control the gain of that stage. For a received signal of high eld intensity, a relatively large negative bias is developed to reduce the gain of amplifier tube 4i. This reduces the magnitude of the alternating potential developed in the output circuit of the amplifier tube El and, hence, reduces the alternating potential supplied through condenser 56 to the circuit I0 of the receiver, thereby reducing the receiver sensitivity inversely in accordance with the eld intensity of the received signal.

When the gain of quench amplifier ill is reduced, the alternating voltage applied to rectifier 50 is also reduced, thereby diminishing the magnitude of the derived unidirectional potential which is applied to the anode of amplifier 54. The pulse T that is developed by system 58 when it is keyed by a received signal is, therefore, translated by amplifier l54 at a reduced amplitude to the step-up transformer Il and to the radio-frequency oscillator circuit lil, the oscillations of which are controlled by this pulse of reduced amplitude. Consequently, the field intensity of the transmitted signal which is radiated by antenna 22 is controlled inversely in accordance with the field intensity of the received signal. It will be seen, therefore, that the con- -trol action is eective to control both-the field intensity of the transmitter and the sensitivity of the receiver inversely in accordance with the ileldintensity of the signal received by antenna 22 from a source. Conversely, when a signal of reduced field intensity is received, the gain of quench amplifier tube 4l is increased, thereby increasing the receiver sensitivity accordingly and also increasing the field intensity of the signal which is radiated by the transmitter.

4It will be apparent from the circuit of Fig. 1 that the quench-oscillator system including the quench amplifier 4l and the rectiiler 50 comprises the sole source of anode potential for amplifier 54, which amplifier, in response to a weak signal received by the antenna 22, requires a high anode potential to develop a strongr output signal.v Consequently, at such a time, a source of potential is required which is considerably higher than is needed for the anode of the other tubes, and the quench oscillator system is capable of meeting this peak-potential requirement.

While the arrangement of Fig. 1 discloses a super-regenerative system using a common re- 4 ceiving and transmitting tube, it will be manifest to one skilled in the art that the system can be modified in various ways` for example. to include separate transmitting and receiving tubes operating at the same or different frequencies and in circuit with separate antennas.

While applicant does not wish to be limited to .coiver of a received signal.

any particular circuit values for the embodiment of the invention described in connection with Fig. i, the following set of representative values for the more critical elements are believed to be suitable in this circuit:

. Tube Il Type 2G22 Tube I9 Type 9004 Tubes 50 and 84 Type 6I-16 Tube 4I Type 6V6 ,Tube 54 Type 807 Resistor 20 10,000 ohms Resistors 43 and 66 0.22 megohm Resistor 46 220 ohms Resistor 55 22,000 ohms Resistor 61 100,000 ohms Condenser I3 1 to 3 micromicrofarads Condenser I8 5 micromicrofarads Condensers 41 and 68 0.01 microfarad Condenser 65 0.001 microfarad Condenser 59 0.05 microfarad Inductance l2 0.15 microhenry Step-up transformer I1 Ratio: 1 to 2.8 +B +300 volts -l-Sc |100 volts -C -75 volts Duration of received signal R lmicrosecond Duration of transmitter signal T 10 microseconds Frequency of oscillator I-. 200 megacycles Frequency of quench oscillator 40 200 kilocycles ReferringV now to Fig. 2, there is shown in block form a modified system, in accordance with the invention, for receiving wave signals from a source and translating related wave signals thereto. This system comprises a receiver 10 of the superheterodyne type and a separate transmitter 12 which are interconnected through a control unit 13 which may be similar to the unit 60 of Fig. 1. Transmitter 12 has an antenna system 18, 18 and also is connected in circuit with theoutput circuit of a detector 11 in receiverJD. The superheterodyne receiver comprises, in the order named, an antenna system 1I, 1|, a radio-frequency amplifier 14, a frequency changer 15, an intermediate-frequency amplier 16, and the detector 11. Control unit 13 is connected to the detector 11 and also to one or more stages of radiofrequency amplifier 14, frequency changer 15, and intermediate-frequency amplifier 16 for applying a control potential to these stages. The stages 14-11, inclusive, of the receiver and the transmitter 12 may be of well-known construction so that detailed illustration and description thereof are deemed unnecessary.

Referring briey, however, to the operation of the system just described, Wave signals are intercepted by the antenna 1|, 1I, are selected and amplified in radio-frquency amplifier 14, and are applied to frequency changer where they are converted into intermediate-frequency signals which, in turn, are amplied in intermediatefrequency amplifier 16, and delivered to detector 11. Modulation components of the signals are derived in detector 11 and are applied to the control unit 13 where a control effect is derived which is proportional to the neld intensity at the re- This control effect, when applied to one or more of units 14--16, inclusive, regulates the sensitivity of the receiver inversely in accordance with the field intensity of the received signals. The same control potential, 75v

being applied to the transmitter 12, is utilized to control the iield intensity of the radiated signal which is developed when the transmitter is keyed into operation. The control potential may, for example, be applied to a control element in the modulator circuit of the transmitter. Modulation components derived by detector 11 are also supplied to conventional circuits in the transmitter 12 to trigger it into operation in response to each detected signal or to predetermined ones thereof.

In summary, therefore, the superheterodyne receiver 10 comprises means at a point for receiving Wave signals from a source (not shown), and the transmitter 12 comprises means for transmitting related wave signals back to the source. Control unit 13 comprises means responsive to the field intensity of the received wave signal at the abovementioned point for deriving la control eifect, while conventional circuits of the transmitter 12 comprise means responsive to the control effect for controlling the field intensity, at the abovementioned point, of the related transmitted signals inversely in accordance with the field intensity of the received signal. One or more stages of units 14, 15 and 16 comprise means responsive tothe control eiect developed in unit 13 to control the sensitivity of the means for receiving wave signals inversely in accordance with the field intensity of the wave signal received bythe antenna system 1l, 1 I.

As used in the instant specication, the term related wave signal is employed broadly to denote any type of signal which is transmitted by a responding unit of a two-way communication system in response to a wave signal which is received from a source. This language is intended to include a wave signal which is amplitude, phase. or frequency-modulated, a reflected wave signal, an unmodulated carrier-wave signal, or a supersonic wave signal.

While there have been described what are at present considered to be the, preferred embodi ments of this invention, it will be obvious to those skilled in the art that various changes and modiiications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A radio receiver-transmitter system comprising: means at a point for receiving from a rem-ote radio transmitting station during spaced receiving intervals radio signals having a field intensity at said point which may vary and for transmitting during intervals intervening said receiving intervals reply radio' signals; means responsive to the ileld intensity of a radio signal received during a receiving interval for deriving a. control effect having a duration coextensive with the next succeeding interval during which a reply radio signal is transmitted; and a control system responsive to said control effect for controlling the eld intensity at said point of said reply radio signal, transmitted during said next succeeding intervening interval, inversely in accordance with the eld intensity of said radio signal received during said receiving interval.

l2. A radio receiver-transmitter system comprising: means at a point for receiving from a remote radio transmitting station during spaced receiving intervals radio signals having a field intensity at said point which may vary and for transmitting during intervals intervening said receiving intervals reply radio signals; means responsive to the iield intensity of a radio signal received during a receiving interval for deriving a control eil'ect having a duration coextensive with at least the next succeeding receiving interval and including y an intervening transmission interval; and a control system responsive to said control effect for controlling the sensitivity of said first-mentioned means during said next succeeding receiving interval and for controllingthe eld intensity at said point of said reply radio signal, transmitted during said intervening transmission interval inversely in accordance with the field intensity of said radio signal received during said receiving interval. i

3. A radio receiver-transmitter system comprising: means at a point for receiving from a remote radio transmitting station during spaced receiving intervals pulse-modulated radio signals havradio signals; means responsive to the field n.

tensity of a pulse-modulated radio signal received during a receiving interval for deriving a control edect having a duration coextensive with the next succeeding interval during which a pulse-modulated radio signal is transmitted; and a control system responsive to said control eiiect for controlling the field intensity at said point of said pulse-modulated radio signal, transmitted during said next succeeding intervening interval, inversely in accordance with the field intensity of said pulse-modulated signal received during said receiving interval.

i. A radio receiver-transmitter system comprising: means at a point for receiving from a remote radio transmitting station `during spaced receiving intervals radio signals having a field lntensity at said point which may vary and for transmittingduring intervals intervening and re-` ceiving intervals reply radio signals; means responsive to the field intensity of a radio signal during a receiving interval for deriving a control eHect having a duration coextensive with the next succeeding interval during which a reply radio signal is transmitted; and a control system responsive to said control effect for so controlling the energization of said mst-mentioned means during said next-succeeding interval that the iield intensity at said point of said reply radio signal, transmitted during said next succeeding interval, varies inversely in accordance with the eld intensity oi said radio signal received during said receiving interval.

5. A radio receiver-transmitter system comprising: means at a point for receiving from a remote radio transmitting station during spaced receiving intervals radio -signals having a iield intensity at said point which may vary and for transmitting during intervals intervening said receiving intervals reply radio signals; means responsive to said received radio signals for developing auxiliary signals, means for utilizing said auxiliary signals to modulate said first-mentioned means during said intervening intervals to produce said reply radio signals, means responsive to the iield intensity of a radio signal received during a receiving interval for deriving a control effect having a duration coextending with the next succeeding interval during which a reply radio signal is transmitted; and a control system responsive to said control effect and coupled to said utilizing means for controlling the eld intensity at said point of said reply radio signal, transmitted during said next succeeding intervening interval, inversely in accordance with the field intensity of said radio signal received during said receiving interval.

6. A wave-signal translating -system comprising: regenerative means at a point for receiving wave signals from a remote source and for transmitting related wave signals in rely thereto; means -responsive to the eld intensity of received wave signals at said point for deriving a control effect; and a control system responsive to said control efect and including quench-oscillator means for controlling regeneration in said regenerative means during receiving intervals to provide gain controlled superregenerative reception and for controlling the eld intensity at said point of said related transmitted Wave signals developed in said regenerative means during transmission intervals inversely in accordance With the iield intensity of said received Wave signals at said point.

7. A Wave-signal translating system comprising: regenerative means at a point for receiving wave signals from a remote source and for transmitting related signals in reply thereto; means responsive to the field intensity of received wave signals at said point for deriving a control eiiect; and a control system responsive to said control effect-and including quench-oscillator means for controlling regeneration in said. regenerative means during receiving intervals to provide gaincontrolled superregenerative reception and for controlling the field intensity at said point of said related transmitted wave signals developed in said regenerative means during transmission intervals and the sensitivity of said regenerative means during said receivim intervals for said received Wave signals inversely in accordance with the field intensity of said received Wave signals at said point.

- LEONARD R. MALLING.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,721,492 Wurst July 16, 1929 2,924,138 Armstrong Dec. 1'?, 1935 2,045,224 Gerhard June 23, 1936 2,164,344 Norvvine July 4, 1939 2,206,146 Wright July 2, 1940 2,268,643 Crosby Jan. 6, 1942 2,273,945 Fisher Feb. 24, 1942 2,365,187 Giannini et al Dec. 19, 1944 

